The long-range objective of this research is to identify and understand the distribution of positional information that governs stereotyped axon growth and patterned synaptogenesis. The work uses experimental embryological techniques to transplant eye primordia and pieces of neural tube. This alters the normal spatial or numerical relationship between the embryonic retina and the developing central nervous system (CNS). Proposed experiments will use autoradiographic, histochemical, behavioral, electrophysiological and ultrastructural techniques to study: 1) the determinants of positional selectivity in ectopic and normal optic tracts, 2) the extrinsic directional cues that cause optic nerve fibers to ascend or descend the CNS, 3) distinguish those aspects of retinotectal connectivity that are intrinsic to the retinal ganglion cells themselves, 4) determine whether central visual nuclei are topographically connected when the brain develops without any optic nerve input, 5) identify the competitive interactions that cause eye-specific segregation of optic fiber tectal terminations in a pattern reminiscent of ocular dominance columns. This research will be conducted on anuran (Rana pipiens) material. However, the results of these studies should reveal basic principles of vertebrate neural pathway development which can then be applied to the prevention and treatment of congenital visual abnormalities and general neurological disorders in man himself.